Refactor template system

[BigBlueHat]

There's a tricky balance between flexibility for designers/developers and consistent feature delivery (RDFa) among BlueInk sites. Try to balance that...simply.

[BigBlueHat]

Right now, all BlueInk items need the following intro properties--so they can be found and made draggable:

<div blueink-component="page-item" data-item-id="{{_id}}" data-item-index="{{_blueink.index}}">

It doesn't have to be a div, but it does need those 3 attributes.

Ideally, there's some better, more semantic way to do this, such as:

<div typeof="schema:WebPageElement" about="...baseurl??...{{_id}}">
  <meta property="position" content="{{_blueink.index}}" />

However, that's...
a. a bit more complicated
b. requires an absolute URL for the value of about (which mucks up the offline-friendliness of BlueInk a bit...)
c. may be tricky / DOM-parse-heavy to extract the bits needed

Still thinking on it, though.